Field-effect transistors (FETs) are three-terminal devices each having a gate electrode, a source electrode, and a drain electrode. An FET is an electronically active device for switching a current between the source electrode and the drain electrode by applying a voltage to the gate electrode to control the current flowing in a channel layer. In particular, an FET having a channel layer of a thin film disposed on an insulating substrate of ceramics, glass, or plastic is called a thin-film transistor (TFT).
TFTs are fabricated by using thin-film technology and advantageously can be readily formed on a substrate having a relatively large area. With advances in manufacturing processes which enables miniaturization of such transistors device and ultra-low leakage performance, therefore, TFTs are widely used as driving devices for electronic devices, such as integrated circuits (ICs) and flat-panel displays (e.g. liquid-crystal displays).
However, there are still drawbacks concerning on the difficulty for filling gate oxide material into a gap disposed between the source electrode and the drain electrode as well as the problems of channel damage which may limit the device further scaling down, during the process for fabricating TFTs.
Therefore, there is a need of providing an improved semiconductor transistor device and method for fabricating the same to enable miniaturization thereof and obviate the drawbacks encountered from the prior art.